Question

which transformation is a rigid transformation?

Explanation:

A rigid transformation preserves the side - lengths and angle - measures of a figure. In the first option, the corresponding sides and angles of the pre - image $\triangle DEF$ and the image $\triangle D'E'F'$ are congruent. Rigid transformations include translations, rotations, and reflections. The first figure shows a transformation where the shape and size are maintained, which is characteristic of a rigid transformation. The second and third options show changes in size (dilation), which is a non - rigid transformation.

Answer:

The first transformation (left - most pair of triangles)